Wöhlerit
| Wöhlerit | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Na 2 Ca 4 ZrNb [F | O 3 | (Si 2 O 7 ) 2 ] |
|
Mineral class (and possibly department) |
Silicates and germanates - group silicates (sorosilicates) |
|
System no. to Strunz and to Dana |
9.BE.17 ( 8th edition : VIII / C.11) 56.02.04.05 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic sphenoid; 2 |
| Room group (no.) | P 2 1 (No. 4) |
| Lattice parameters |
a = 10.82 Å ; b = 10.24 Å; c = 7.29 Å β = 109.0 ° |
| Formula units | Z = 2 |
| Frequent crystal faces | {100} |
| Twinning | according to (100), pseudorhombic twins |
| Physical Properties | |
| Mohs hardness | 6 to 6.5 |
| Density (g / cm 3 ) | measured: 3.40 to 3.44; calculated: 3.42 |
| Cleavage | clear after {010}, indistinct after {100} and {110} |
| Break ; Tenacity | shell-like to splintery; brittle |
| colour | light yellow to yellow, brown, gray |
| Line color | light yellow |
| transparency | transparent to translucent |
| shine | Glass gloss, resin to fat gloss, matt |
| Crystal optics | |
| Refractive indices |
n α = 1.700 to 1.705 n β = 1.716 to 1.720 n γ = 1.726 to 1.728 |
| Birefringence | δ = 0.026 |
| Optical character | biaxial negative |
| Axis angle | 2V = 70 to 77 ° (measured); 70 to 76 ° (calculated) |
| Pleochroism | weak: X = Y = light yellow to almost colorless; Z = wine yellow |
Wöhlerite is a rarely occurring mineral from the mineral class of "silicates and germanates". It crystallizes in the monoclinic crystal system with the chemical composition Na 2 Ca 4 ZrNb [F | O 3 | (Si 2 O 7 ) 2 ], so it is a complex composition of sodium - calcium - zirconium - niobium - silicate with fluorine and oxygen as additional anions . Structurally, Wöhlerite belongs to the group silicates ( sorosilicates ).
Wöhlerite is transparent to translucent and develops mostly thick tabular to prismatic crystals and pseudorhombic twins , but also granular aggregates from light yellow to yellow, brown or gray in color with light yellow streak color . Uninjured crystal surfaces have a glass-like gloss , whereas fractured surfaces have a resinous to greasy gloss .
With a Mohs hardness of 6 to 6.5, Wöhlerite is already one of the hard minerals that, like the reference mineral orthoclase (6), can be scratched with a steel file.
Special properties
In front of the soldering tube in platinum pliers, Wöhlerit can be heated until it glows without it changing. However, when the heat is increased, the mineral melts to a yellowish glass without forming bubbles.
Etymology and history
Wöhlerite was first discovered in the syenite pegmatite passages of some quarries, including on the island of Løvøya (Løvø, Lovoya, Lövö, Lövöe) in the Langesund Fjord near the town of Brevik in the Norwegian province of Telemark and described in 1843 by Theodor Scheerer (1813-1875), who named the mineral after the German chemist Friedrich Wöhler .
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the Wöhlerite belonged to the mineral class of "silicates and germanates" and there to the department of "group silicates (sorosilicates)", where together with Låvenit he created the "Wöhlerit-Låvenit- Group "with the system no. VIII / C.11 and the other members Baghdadit , Burpalit , Dovyrenit , Hiortdahlit , Janhaugit , Låvenit, Marianoit , Niocalit and Normandit formed.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also classifies Wöhlerite in the category of "group silicates (sorosilicates)". However, this is further subdivided according to the structure of the silicate groups, the possible presence of further anions and the coordination of the cations involved , so that the mineral is classified in the sub-section “Si 2 O 7 groups with additional anions; Cations in octahedral [6] and greater coordination ”can be found, where together with baghdadite, burpalite, cuspidin , hiortdahlite, janhaugite, Låvenite, marianoite, niocalite and normandite, the“ cuspid group ”with the system no. 9.BE.17 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Wöhlerite to the class of "silicates and germanates" and there in the department of "group silicates: Si 2 O 7 groups and O, OH, F and H 2 O" a. Here it is together with Cuspidin in the " Cuspidin-Wöhlerit Group " with the system no. 56.02.04 and the other members Baghdadit, Burpalit, cuspidine Hainit , Hiortdahlit, Janhaugit, jennite , Kochit , Komarovit , Kristiansenit , Låvenit, Marianoit, Mongolit, Natrokomarovit , Niocalit, Rosenbuschite and Suolunit "within the subdivision group silicates: Si 2 O 7 Groups and O, OH, F and H 2 O with cations in [4] and / or> [4] coordination ”.
Education and Locations
Wöhlerit formed as an ancillary part in late-stage crystallization alkaline pegmatites , but is also found in nepheline - syenites , fenite and carbonatites . According to its formation conditions he can with many other minerals associated occur, so among other Aegirin , albite , Astrophyllit , Betafit , biotite , Cancrinit , Katapleiit , Eudialyt , Ferrohornblende , fluorite , Latrappit , Låvenit , mosandrite , nepheline, pyrochlore , Rosenbuschite and zirconium niobium-containing and Perovskite and zirconolite .
As a rare mineral formation, Wöhlerite could only be detected at a few sites, whereby so far (as of 2014) around 70 sites are known. In addition to its type locality Løvøya, the mineral occurred in Norway in several places in the Langesundsfjord and in the areas around Bjørkedalen, Langangen and Mørje in the province of Telemark . It was also discovered in many places in Vestfold Province .
In Germany, Wöhlerit has so far been found mainly in the Rhineland-Palatinate Vulkaneifel , including at Niedermendig , at Wingertsberg and at Krufter Ofen near Lake Laacher , in the “Löhley” quarry near Üdersdorf and at Hüttenberg in the municipality of Glees . It also occurred in the Badloch am Badberg quarry in the Kaiserstuhl in Baden-Württemberg.
Other locations include Angola, Australia, Greenland, Guinea, Italy, Canada, Malawi, Mali, Romania, Russia, Sweden and the United States of America (New Hampshire).
Crystal structure
Wöhlerite crystallizes monoclinically in the space group P 2 1 (space group no. 4) with the lattice parameters a = 10.82 Å ; b = 10.24 Å; c = 7.29 Å and β = 109.0 ° as well as two formula units per unit cell .
See also
literature
- Th. Scheerer: About the Wöhlerite, a new mineral species. In: Annals of Physics and Chemistry. Volume 59, 1843, pp. 327-336 ( PDF 663 kB ).
- RI Shibayeva, NV Belov: Crystal structure of wöhlerite, Ca 2 Na (Zr, Nb) Si 2 O 7 (O, F) 2 . In: Doklady Akademii Nauk SSSR. Volume 146, 1960, pp. 897-900 ( PDF 269.4 kB ; Russian).
- Michael Fleischer : New mineral names. In: American Mineralogist. Volume 46, 1961, pp. 241-244 ( PDF 297.7 kB ).
- M. Golyshev, LP Otroshchenko, VI Simonov, NV Belov: Refining the atomic structure of wöhlerite, NaCa 2 (Zr, Nb) [Si 2 O 7 ] (F, O) 2 . In: Soviet Physics - Doklady. Volume 8, 1973, pp. 287-289.
- M. Mellini, S. Merlino: Refinement of the crystal structure of wöhlerite. In: Tschermaks Mineralogische und Petrographische Mitteilungen. Volume 26, 1979, pp. 109-125.
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke , Stuttgart 1978, ISBN 3-432-82986-8 , pp. 694 (first edition: 1891).
Web links
- Mineral Atlas: Wöhlerite (Wiki)
- Webmineral - Wöhlerite
- Database-of-Raman-spectroscopy - Wöhlerite
- American-Mineralogist-Crystal-Structure-Database - Wöhlerite
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 576 .
- ^ A b Helmut Schrätze, Karl-Ludwig Weiner: Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin / New York 1981, ISBN 3-11-006823-0 .
- ↑ a b c d Wöhlerite. In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America. 2001. ( PDF 76 kB )
- ↑ a b c d Mindat - Wöhlerite
- ↑ a b Th. Scheerer: Ueber den Wöhlerit, a new mineral species. In: Annals of Physics and Chemistry. Volume 59 1843, pp. 327–336 ( PDF 663 kB )
- ↑ Mindat - Number of localities for Wöhlerite
- ↑ Find location list for Wöhlerite at the Mineralienatlas and at Mindat